// ========================================================================
// Copyright (c) 2002-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================

package org.eclipse.jetty.server;

import java.util.Enumeration;
import java.util.List;
import java.util.StringTokenizer;

import org.eclipse.jetty.util.LazyList;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

/* ------------------------------------------------------------ */
/**
 * Byte range inclusive of end points.
 * 
 * <PRE>
 * 
 *   parses the following types of byte ranges:
 * 
 *       bytes=100-499
 *       bytes=-300
 *       bytes=100-
 *       bytes=1-2,2-3,6-,-2
 * 
 *   given an entity length, converts range to string
 * 
 *       bytes 100-499/500
 * 
 * </PRE>
 * 
 * Based on RFC2616 3.12, 14.16, 14.35.1, 14.35.2
 * 
 * @version $version$
 */
@SuppressWarnings({ "rawtypes" })
public class InclusiveByteRange
{

	private static final Logger LOG = Log.getLogger(InclusiveByteRange.class);

	long first = 0;
	long last = 0;

	public InclusiveByteRange(long first, long last)
	{
		this.first = first;
		this.last = last;
	}

	public long getFirst()
	{
		return first;
	}

	public long getLast()
	{
		return last;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param headers Enumeration of Range header fields.
	 * @param size Size of the resource.
	 * @return LazyList of satisfiable ranges
	 */
	public static List satisfiableRanges(Enumeration headers, long size)
	{
		Object satRanges = null;

		// walk through all Range headers
		headers: while (headers.hasMoreElements())
		{
			String header = (String)headers.nextElement();
			StringTokenizer tok = new StringTokenizer(header, "=,", false);
			String t = null;
			try
			{
				// read all byte ranges for this header 
				while (tok.hasMoreTokens())
				{
					try
					{
						t = tok.nextToken().trim();

						long first = -1;
						long last = -1;
						int d = t.indexOf('-');
						if (d < 0 || t.indexOf("-", d + 1) >= 0)
						{
							if ("bytes".equals(t))
								continue;
							LOG.warn("Bad range format: {}", t);
							continue headers;
						}
						else if (d == 0)
						{
							if (d + 1 < t.length())
								last = Long.parseLong(t.substring(d + 1).trim());
							else
							{
								LOG.warn("Bad range format: {}", t);
								continue;
							}
						}
						else if (d + 1 < t.length())
						{
							first = Long.parseLong(t.substring(0, d).trim());
							last = Long.parseLong(t.substring(d + 1).trim());
						}
						else
							first = Long.parseLong(t.substring(0, d).trim());

						if (first == -1 && last == -1)
							continue headers;

						if (first != -1 && last != -1 && (first > last))
							continue headers;

						if (first < size)
						{
							InclusiveByteRange range = new InclusiveByteRange(first, last);
							satRanges = LazyList.add(satRanges, range);
						}
					} catch (NumberFormatException e)
					{
						LOG.warn("Bad range format: {}", t);
						LOG.ignore(e);
						continue;
					}
				}
			} catch (Exception e)
			{
				LOG.warn("Bad range format: {}", t);
				LOG.ignore(e);
			}
		}
		return LazyList.getList(satRanges, true);
	}

	/* ------------------------------------------------------------ */
	public long getFirst(long size)
	{
		if (first < 0)
		{
			long tf = size - last;
			if (tf < 0)
				tf = 0;
			return tf;
		}
		return first;
	}

	/* ------------------------------------------------------------ */
	public long getLast(long size)
	{
		if (first < 0)
			return size - 1;

		if (last < 0 || last >= size)
			return size - 1;
		return last;
	}

	/* ------------------------------------------------------------ */
	public long getSize(long size)
	{
		return getLast(size) - getFirst(size) + 1;
	}

	/* ------------------------------------------------------------ */
	public String toHeaderRangeString(long size)
	{
		StringBuilder sb = new StringBuilder(40);
		sb.append("bytes ");
		sb.append(getFirst(size));
		sb.append('-');
		sb.append(getLast(size));
		sb.append("/");
		sb.append(size);
		return sb.toString();
	}

	/* ------------------------------------------------------------ */
	public static String to416HeaderRangeString(long size)
	{
		StringBuilder sb = new StringBuilder(40);
		sb.append("bytes */");
		sb.append(size);
		return sb.toString();
	}

	/* ------------------------------------------------------------ */
	@Override
	public String toString()
	{
		StringBuilder sb = new StringBuilder(60);
		sb.append(Long.toString(first));
		sb.append(":");
		sb.append(Long.toString(last));
		return sb.toString();
	}

}
